Home Node-Bs (HNBs) for Universal Mobile Telecommunications System (UMTS) and Home e-Node-Bs (HeNBs) for Long Term Evolution (LTE) (collectively, “Home Node-Bs” (HNBs)), have been introduced in Release 8 of the 3rd Generation Partnership Project (3GPP) standard, for example, to increase cellular coverage and overall system throughput. HNBs are physical devices (e.g., similar to wireless local area network (WLAN) access points (APs)) that provide access to UMTS and/or LTE services over extremely small service areas (or cells), such as private homes, small offices and coffee shops. As opposed to WLAN APs, which are generally accessible by wireless devices within their ranges, access to HNBs may be limited to smaller, more select groups of users referred to as closed subscriber groups (CSGs). Similar to WLAN APs, however, HNBs connect their users' wireless devices to the HNB operator's core network. For HNBs, the connection may be established using, for example, an internet connection (e.g., a digital subscriber line (DSL)). By way of example, a coffee shop owner (or subscriber) may choose to deploy an HNB in his or her shop to provide patrons (the CSG in this example) with a stronger wireless connection than may otherwise be available inside the shop. Due to their use in small service areas, HNBs may be densely deployed and, accordingly, located within the coverage area of one or more macro Node-Bs.
To enable certain functionalities for wireless devices or wireless transmit/receive units (WTRUs), such as handover (HO) between network nodes, it may be necessary for the WTRU to perform measurements, for example, on other frequencies or systems. To perform these measurements, the WTRU may require gaps.
Inter-frequency measurement reporting rules do not cover scenarios where it may be preferable for the WTRU to handover from a macro cell frequency to an HNB frequency, even if the quality of the macro cell frequency is still acceptable. The network typically configures the WTRU for compressed mode with gaps to measure other frequencies when the WTRU is at the border of one or more cells and needs to handover to another frequency.
The inter-frequency measurement reporting rules rarely apply to HNBs, which may be, for example, deployed in private homes localized anywhere in the macro cell coverage area (as described above). Nevertheless, a user may prefer to handover from a macro cell to an HNB, even if the quality of the frequency of the serving macro cell is above a predetermined threshold. To handover the WTRU from a macro cell to an HNB, the network may need to configure the user's WTRU for compressed mode in order to detect the HNB primary scrambling codes (PSCs) (applicable to UMTS HNBs) or physical cell identities (PCIs) (applicable to LTE HNB) on other frequencies.